Charles Blair, 69, an aviator who set a transatlantic speed record for piston-engine airplanes in 1951, died Saturday when his plane, a Grumman Goose, capsized after attempting an emergency landing in heavy seas about a mile west of St. Thomas in the Virgin Islands.

He was the founder of Antilles Airboat, an airline in the Virgin Islands. He and three others died in the crash landing. Seven others were rescued.

Mr. Blair was a transatlantic pilot for Pan American Airways when he purchased a "civilianized" P-51 Mustang from a Hollywood stunt pilot in 1950.

In January 1951, he set the transatlantic speed record from New York to London for piston-engine aircraft at 7 hours and 43 minutes, which stands to this day.

Mr. Blair developed new navigation methods so a polar route between Europe and North America could be opened.A magnetic compass is unreliable near the poles, as military and civilian aircraft had to fly a more southerly route that was much longer, but, in using a magnetic compass, safer.

His method utilized sunlines at precomputed points and times as a means of maintaining direction across the polar region. To prove the method, he again took to the air with a modified Mustang, the Excalibur III, from Barufoss, Norway, on May 29, 1951. He flew over the North Pole and covered more than 7,500 miles in 10 hours, 27 minutes before landing at his planned destination at Point Barrow, Alaska.

He then flew nonstop to New York from Alaska in 9 hours, 31 minutes, landing on May 30.

Some experts said that the significance of Mr. Blair's polar flight was that it proved that the Arctic Ocean was no longer a barrier against air attack in military strategy.

In 1952, he was invited by the Strategic Air Command to work as a part-time consultant on long-range fighter tactics.

Mr. Blair continued to work as a pilot for Pan American, but also was commissioned a brigadier general in the Air Force. In 1956 he commanded the Air Force's Operation Sharkbat, a nonstop flight of jet fighters across the Atlantic, and in 1959, Operation Julius Caesar, the first flight of jet fighters to cross the Arctic and North Pole.

He retired from Pan Am in 1969, and moved to the Virgin Islands.

Mr. Blair was a native of Buffalo, N.Y. He studied aeronautical engineering at the University of Michigan and mechanical engineering at the University of Vermont, from which he graduated in 1931. He then served for about three years in the Navy and was a graduate of the Navy flight school in Pensacols.

He was chief pilot for the old American Export Airlines (AEA) during the 1940s, when he first flew flying boats across the Atlantic.

During World War II, he remained a civilian, piloting military and diplomatic passengers and top priority cargo between the United States and the European combat theaters for AEA.

Mr. Blair held a number of awards, including the Harmon Trophy, as the outstanding aviator of 1951 for his flight over the North Pole.

Survivors include his wife, motion-picture actress Maureen O'Hara, of the home in St. Croix; his mother, Grace M. Blair, of Fletcher, Vt.; a daughter, and three sons.

The family suggests that expressions of sympathy be in the form of contributions to either the Boys Club or the Boy Scots in St. Croix.